Dry powder fire extinguishing medium



n tcd S ates Paten r 2,881,188 DRY POWDER ,n in ien w nni a ay No-Drawing. pplicatio Ma lzal ass S i l 89 55495115 Claims priority, application GermanyMayQl, 1 954 =3 laims- 1 -115 Th in n ef s. o ay l pwde st ex n uis in; m di m which ex n uish r --ti s co qu d a d Lea eous substances as well as fires"o f 5olid substanceswhich give birth to glowingremnants when b g. There have already been 'frnade fknown powder fire extinguishing mediums of th'e inost walnuts compositions:

almjostall powder-like chemicals which are available for not too highprices have beep proposed for thistpurpose.

"fires and which is able to gexti'nguish, beside fifires of liquid and gaseous substances, alsodires of solid 'substances, i.e. in which glowing remnants are given birth to.

According to the invention, the dry powder extinguishing medium consists substantially of sulphuric salts of an alkaline metal with ammonium phosphate and bicarbonates. When using the new dry powder fire extinguishing medium, there takes place beside the mechanical extinguishing effect known with all dry powder extinguishing mediums also, due to the extinguishing mediums violently striking upon the seat of the fire under the action of the propelling agent, the following specific effect: above the seat of the fire a cloud of extinguishing gas smothering the fire springs up, and, in addition, when .solid substances burn, the burning object is covered with a thick crust which prevents the respective object to be set again ablaze. This incrustation takes place above all because in the heat of the seat of the fire there is given birth to an easily flowing fluid of molten sodium metaphosphate (NaPO which is produced intermediarily from the acidic sodium pyrophosphate which has formed as an intermediate product, and some sodiumsilicate.

It is already known, it is true, that bicarbonates, such as sodium bicarbonate, give off on the seat of the fire gaseous carbonic acid which assists the extinguishing effect. It has also been proposed to use ammonium phosphate in aqueous solution for the production of coatings serving to check or stop the spread of the fire. As contrasted therewith, it is new in the present invention to use the abovenamed ingredients in the respective combination in powder-like state as a dry powder extinguishing medium, whereby now a dry powder extinguishing medium is available which can be used with fires of all kinds such as it has been striven for by the skilled in the art already for a long time and without any practical success.

The dry powder extinguishing medium may contain, for example, sodium sulphate or ammonium sulphate. It has been found that especially favourable efiects can be obtained if the ammonium sulphate and the am- 2,881,138 R en es Aprmoniumphosphate are added .to the drypowderfire extinguishing medium in the form of a compound crystallisate. This compound crystallisate is produced ginlthe following manner: Technical calcium phosphates (nat'- ural phosphorites') are bl enediby means ofsiilp'hii 0 acid arid the precipitated slurry of gypsum is th .filtrated.' "From theremaining solution "of "orthopho hone acid "there is "produced a'compound acid by furtherafid ingof concentrated sulphuric acid. Into 'this jcompoun'd acid there is introduced gaseous 'ammoriiaor amiixtur'e of gases "containing ammonia until complete neutrahsation. Hereafter, "the solution of concentrated e nipbnim salts produced in this 'way is broken up ffinely to a d .fi ry i po e y the oppo l 'ili of'the rising warm It is also'possible to 19w tempe a w dyi t lgmr fiad q y ,tallis'ate obtained directly from the solution.

"The mo ne mix e o amm um ,nh s ha c and amm i m l a Pr d d ad s n 10 the ahovesaid method is nothygroscopic and totally neutral. I does no o n e a t e o ee d le tin s- :T ext hing p de a ni g h [cl b ur: crystallisate has, therefore, .beside .its surprising exfjt ns in e s n p c a y oo w n c pa ty arid'canbe stored even for a very long :time.

"The ftollo'w'ing .examples illustrate .theinyention:

Example 1 24 t 72 pa t y we h o a o un s tfil i a e of ammonium phosphate and ammonium siilphateare mixed with 76 to 28 parts by weight of a finely pulverized mixture which contains the following ingredients: sodium bicarbonate, ammonium bicarbonate, oxide of zinc, and precipitated colloidic silicic acid (silica gel). To the mixture there have been finally added small amounts of argentic chloride, stearic acid, and fullers earth.

The colloidic and finely subdivided silicic acid (silica gel) contained in an intimate mixture with the ammonium bicarbonate acts, due to an especially high and selective adsorptive capacity with respect to C0 and NH continually as a stabilizating substance and prevents the premature sublimation of the ammonium carbonate. At the same time, the sodium silicate which, beside the sodium phosphate, is given birth to on the seat of the fire by thermic effect constitutes a specific effective protection for the glowing remnants of the seat of the fire against their being set again ablaze. The small amounts of heavy metal salts (AgCl) contained in the mixture have been recognized as a specific effective anti-catalyst in connection with the other ingredients of the mixture during the combustion process.

Example 2 30-40 parts by weight of sodium sulphate (Na SO calcined, finely pulverized,

25-35 parts by weight di-ammonium phosphate, finely pulverized, and

4525 parts by weight of a finely pulverized mixture consisting of ammonium bicarbonate, oxide of zinc, and silica gel.

To the abovenamed mixture there are added small amounts of argentic chloride, stean'c acid, and fullers earth.

Example 3 kg. ammonium sulphate ((NH SO of technical quality are mixed with 3 kg. tricalcium phosphate and ground in a sieveless pivot mill (premixture sulphate).

100 kg. diammoniumhydrogenphosphate (if -technical* are mixed with kg. tric alcium phosphate andground in a sieveless pivot-mill (premixture phosphate).

the. examples illustrated,.but I-desire it to be under- I stood that I reservethe privilege of resorting to all changes to-which the invention is susceptible, this latter being defined andlimited only by the terms of the ap pended claimsi, i I

Haying thus described the invention, what I claim as new, and desire-to secure by Letters Patent is:

' '1; As a new composition-of matter, a dry powder .adapted,t ,extinguishfires originating from solid, liquid arid'g'as'e ou's' combustible materials, consisting essentially ofan' intimate mixture including as essential ingredients at lle'ast 30% by weight, of salts belonging to the group consisting of alkali metal sulfates and ammonium sulfates, a'tfleasft 16 /2 by weight of an ammonium phosphate, at

least 16% by weight of a bicarbonate, said mixture being adapted to extinguish fires originating from solid, liquid and gaseous'suhstances and, when applied tolburning solid material to extinguish glowing portions thereof.

2. As a new composition of matter, a dry power adapted to extinguish fires originating from. solid, liquid and, gaseous combustible materials, consisting essentially v v i v 4 1 of an intimate mixture of between 30 and parts by weight of sodium sulfate, between 25 and 35 .parts by weight of diammonium phosphate, and between and 25 parts by weight of ammonium bicarbonate, said mixture being adapted to extinguish fires originating from solid, liquid and gaseous substances and when applied to burning solid material to extinguish glowingportions thereof. I I v '3'. As anew composition of matter, a dry powder adapted to extinguish fires originating from solid, liquid and gaseous combustible materials, consisting essentially of an intimate mixture of approximately 64 parts by weight of ammonium'sulfate," approximately 16.5 parts by weight'of-diammonium hydrogen phosphate, approximately 2.5 parts by weight of tri-calcium phosphate, approximately 16' parts by weight of sodium bicarbonate and approximately 1 part by weight of magnesium stearate, said mixture being adapted to extinguish fires origi- Rating-non solid, liquid-and gaseous substances and when applied to' bur'ning solid material to extinguish glowing portions thereof.

' References Cited in the file of this patent UNITED STATES PATENTS 502,867 Schuler Aug. 8, 1893 1,271,506 "Ferguson July 2, 1918 1,793,420 v Block Feb. 17, 1931 2,472,539 I 'McGlenn June 7, 1949 -2-,7 68,'952 Anthony Oct. 30, 1956 1 FOREIGN PATENTS 73s Great Britain 1901 721,168 Great Britain 1909 Great ta n. -.-,-.--.-.a-.- Ma .2 

1.
 3. AS A NEW COMPOSITION OF MATTER, A DRY POWDER ADAPTED TO EXTINGUISH FIRES ORIGINATING FROM SOLID, LIQUID AND GASEOUS COMBUSATIBLE MATERIALS, CONSISTING ESSENTIALLY OF AN INTIMATE MIXTURE OF APPROXIMATELY 64 PARTS BY WEIGHT OF AMMONIUM SULFATE, APPROXIMATELY 16.5 PARTS BY WEIGHT OF DIAMMONIUM HYDROGEN PHOSPHATE, APPROXIMATELY 2.5 PARTS BY WEIGHT OF TRI-CALCIUM PHOSPHATE, APPROXIMATELY 16 PARTS BY WEIGHT OF SODIUM BICARBONATE AND APPROXIMATELY 1 PART BY WEIGHT OF MAGNESIUM STEARATE, SAID MIXTURE BEING ADAPTED TO EXTINGUISH FIRES ORIGINATING FROM SOLID, LIQUID AND GASEOUS SUBSTANCES AND WHEN APPLIED TO BURNING SOLID MATERIAL TO EXTINGUISH GLOWING PORTIONS THEREOF. 